I've been using regular 87 octane gas from a regular fuel station (always use Shell) for many years, ever since I've owned a boat which has a 200 OX66 Yamaha and my Dad did the same for decades with his Grady White and other boats. I use Startron Enzyme fuel treatment. You can buy it at Wallyworld in an 8oz bottle for $10 but it treats up to 128 gallons (1 oz per 16 gallons). I prefer this over Sta-bil as it prevents phase separation and keeps the fuel fresh for up to 2 years supposedly. Watch out if you buy it at an auto parts store as they sell two different concentrations...one treats at a 1:16 ratio and the weaker one treats at a 1:6 ratio - you think your saving money but you're not. My boat has a 140g fuel tank so filling it at a marina is something I never even considered. I use this in all my yard equipment and Harley too before storage to prevent fuel problems...it works.